Elementary-School Tests Strong Predictors of Adult IQ

Scores on elementary-school achievement tests have a lot to do with IQ and where kids end up later in life, a new study shows.

Researchers administered IQ tests to 219 adults in their mid-40s and compared each person's IQ score to how well he or she had performed on elementary-school achievement tests.

They found that 41 percent of their IQ scores could be accounted for by the school achievement tests, a very strong correlation (slightly higher than the correlation between height and weight in adults, an unrelated pairing that is also strong).

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How well the people did on their tests also predicted, to a lesser extent, their income as adults, their occupational status and the level of education they ended up attaining.

The findings suggest that achievement tests and IQ tests aren't all that different, and that IQ remains consistent over time.

"IQ is typically a very stable trait," said lead researcher Ruth Spinks, a behavioral and cognitive neuroscientist at the University of Iowa.

The study also raises the question of how education influences accomplishment.

People seem to be "locked in" to outcomes at early ages, said Douglas Detterman, a psychologist at Case Western Reserve University in Ohio, who was not involved in the research. "It means we don't know very much about education and optimizing education for particular individuals."

Spinks, however, points out that all of her subjects went to school in Iowa, which has a relatively homogeneous education system, so it's difficult to extrapolate about the effects of education generally nationwide.